Method of hydrocarbon reforming and catalyst precursor

ABSTRACT

Hydrotalcite-like clays, catalysts derived therefrom, and methods of hydrocarbon reforming using the catalyst are disclosed. The hydrotalcite-like clays, which may be calcined to form the catalyst, have the formula [M 2+ .sub.(1-x) M 3+   x  (OH) 2  ] x+  (A n-   x/n ).mH 2  O at an elevated temperature for a time sufficient to decompose A and to dehydrate said compound, wherein M 2+   comprises at least two species of metal ions having a valence of 2+ selected from the group consisting of Cu 2+ , Zn 2+ , Ni 2+ , and Mg 2+ , provided that if M 2+   comprises Mg 2+   at least one of Zn 2+   and Ni 2+   is also present, wherein the atomic ratio of the total of Zn 2+   and Mg 2+   to the total of Cu 2+   and Ni 2+   is up to about 9, inclusive, wherein the total of Zn 2+  and Mg 2+   comprises at least about 5 wt. % of said M 2+   metals; M 3+   is at least one metal ion having a valence of 3+ selected from the group consisting of Al 3+ , Fe 3+ , Cr 3+ , La 3+ , Ce 3+ , and mixtures thereof; x is a number in the range of about 0.1 to about 0.5, inclusive; A is an anion having a charge of -n; n is an integer in the range of 1 to 6, inclusive; and, m is zero or a positive number.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. application Ser. No. 08/897,743filed Jul. 21, 1997, now abandoned the entire disclosure of which isincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to catalysts and catalytic processes forreforming oxygen-containing hydrocarbons and, more specifically, theinvention relates to a method of converting oxygen-containinghydrocarbons to useful products using catalysts derived fromhydrotalcite-like catalyst precursors.

2. Description of Related Technology

The use of metal-containing catalysts in converting oxygen-containinghydrocarbons to useful products (e.g. methanol reforming the conversionof methanol to carbon dioxide and hydrogen by reaction of methanol andwater) is well known. Conventionally, the oxygen-containing hydrocarbonis reacted with excess steam over a catalyst, generally in the form ofmixed metal oxides, such as CuO/ZnO/Al₂ O₃, to produce useful products(e.g., carbon dioxide and hydrogen). The catalysts and processes usedfor steam reforming of oxygen-containing hydrocarbons, however, havesuffered from various disadvantages.

Mixed metal oxide catalysts are readily susceptible to deactivation and,furthermore, the active sites present in mixed metal oxide catalyststend to deactivate at differing rates, which adversely affectsselectivity as well as activity.

Typical methanol reforming (and other) processes of the prior artrequire excess steam to increase the degree of conversion of theprocess, which adds greatly to the energy costs of the process. Someprior hydrocarbon conversion catalysts are difficult to prepare and/orexhibit low activity and/or selectivity. Some prior processes requirethat the hydrocarbon and/or water reactants be supplied to the reactorin gaseous form, which further increases the cost of the process.Further, steam, heat, and time are major factors leading to deactivationof conventional mixed metal oxides due to sintering, which results inthe loss of surface area and formation of aggregates.

SUMMARY OF THE INVENTION

It is an object of the invention to overcome one or more of thedisadvantages described above.

According to the invention, a method of converting oxygen-containinghydrocarbons using a catalyst derived from a hydrotalcite-like compound(i.e., a hydrotalcite-like clay) is provided. The hydrotalcite-likecompound is of the formula [M²⁺.sub.(1-x) M³⁺ _(x) (OH)₂ ]^(x+) (A^(n-)_(x/n)).mH₂ O at an elevated temperature for a time sufficient todecompose A and to dehydrate the compound, wherein M²⁺ comprises atleast two species of metal ions having a valence of 2+ selected from thegroup consisting of Cu²⁺, Zn²⁺, Ni²⁺, and Mg²⁺, provided that if M²⁺comprises Mg²⁺ at least one of Zn²⁺ and Ni²⁺ is also present, whereinthe atomic ratio of the total of Zn²⁺ and Mg²⁺ to the total of Cu²⁺ andNi²⁺ is up to about 9, inclusive, wherein the total of Zn²⁺ and Mg²⁺comprises at least about 5 wt. % of said M²⁺ metals; M³⁺ is at least onemetal ion having a valence of 3+ selected from the group consisting ofAl³⁺, Fe³⁺, Cr³⁺, La³⁺, Ce³⁺, and mixtures thereof; x is a number in therange of about 0.1 to about 0.5, inclusive; A is an anion having acharge of -n; n is an integer in the range of 1 to 6, inclusive; and, mis zero or a positive number.

The hydrotalcite-like compound is prepared by coprecipitating selectedanionic and cationic species under controlled pH and concentrationconditions to form a gel, followed by drying of the gel. The catalyst isformed by calcining the hydrotalcite-like compound.

The invention provides hydrocarbon reforming catalysts and processeswherein the catalysts exhibit excellent activity and selectivity, havelong term hydrothermal stability, and are simple and inexpensive toprepare. The invention allows the efficient production of usefulproducts from liquid feeds.

Other objects and advantages of the invention may be apparent to thoseskilled in the art from a review of the following detailed descriptiontaken in conjunction with the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The catalysts and processes of the invention are broadly applicable tothe reforming of a wide variety of oxygen-containing hydrocarbons("oxygenates") to produce hydrogen and other useful products. Oxygenatesthat may be reformed to useful products according to the inventioninclude various ethers (e.g., dimethyl ether, diethyl ether, and methylethyl ether), alcohols (methanol, ethanol, propanols, and butanols, forexample), and C₂ to C₄ aldehydes and ketones, for example. The inventionis especially applicable to methanol reforming, and while the followingdescription refers to methanol reforming as an example of an applicationof the invention, the scope of the invention is not to be limited bysuch reference.

While other mechanisms may apply (see, for example, Bhattacharyya U.S.Pat. No. 5,498,370 at cols. 3 and 4, and Jiang et al., Applied Catal. A:General 97 (1993) at 145-158 and 245-255), methanol may be reformed by areaction with water to produce carbon dioxide and hydrogen by twogeneral steps, e.g., by decomposition of methanol to carbon monoxide andhydrogen by the reaction:

    CH.sub.3 OH→CO+2H.sub.2

and by reaction of carbon monoxide and water to form carbon dioxide andhydrogen by the following, so-called "water gas shift" reaction:

    CO+H.sub.2 O→CO.sub.2 +H.sub.2.

The overall methanol reforming reaction is thus set forth by thefollowing reaction:

    CH.sub.3 OH+H.sub.2 O→CO.sub.2 +3H.sub.2.

The overall reaction is endothermic, and in the past has typicallyutilized excess steam to drive the conversion of carbon monoxide tocarbon dioxide and hydrogen in the water gas shift reaction.

According to the invention, ethanol may be reformed to produce hydrogenand acetic acid, by the following mechanism. In the presence of acatalyst of the invention, ethanol is dehydrogenated to produce ethylacetate and hydrogen, according to the reaction:

    2CH.sub.3 CH.sub.2 OH→CH.sub.3 CH.sub.2 OCOCH.sub.3 +2H.sub.2.

Ethyl acetate is then hydrolyzed to produce acetic acid by the reaction:

    CH.sub.3 CH.sub.2 OCOCH.sub.3 +H.sub.2 O→CH.sub.3 CH.sub.2 OH+CH.sub.3 COOH.

The overall ethanol reforming reaction is thus as follows:

    CH.sub.3 CH.sub.2 OH+H.sub.2 O→CH.sub.3 COOH+2H.sub.2.

Hence, ethanol and water, in a 1:1 molar ratio, react over a catalyst toproduce acetic acid and hydrogen.

The invention provides a highly efficient reaction system wherein aliquid hydrocarbon (e.g., methanol) and water may be fed to a reactor(which operates at an elevated temperature) at a substantially unimolarratio, if desired. In any event, substantial excesses of expensive steamare not required.

This and other objectives of the invention are provided by the use of acatalyst derived by calcining a hydrotalcite-like compound of theformula [M²⁺.sub.(1-x) M³⁺ _(x) (OH)₂ ]^(x+) (A^(n-) _(x/n)).mH₂ O at anelevated temperature for a time sufficient to decompose A and todehydrate said compound, wherein M²⁺ comprises at least two species ofmetal ions having a valence of 2+ selected from the group consisting ofCu²⁺, Zn²⁺, Ni²⁺, and Mg²⁺, provided that if M²⁺ comprises Mg²⁺ at leastone of Zn²⁺ and Ni²⁺ is also present, wherein the atomic ratio of thetotal of Zn²⁺ and Mg²⁺ to the total of Cu²⁺ and Ni²⁺ is up to about 9,inclusive, and preferably about 0.3 to about 5, inclusive, wherein thetotal of Zn²⁺ and Mg²⁺ comprises at least about 5 wt. % of said M²⁺metals; M³⁺ is at least one metal ion having a valence of 3+ selectedfrom the group consisting of Al³⁺, Fe³⁺, Cr³⁺, La³⁺, Ce³⁺, and mixturesthereof; x is a number in the range of about 0.1 to about 0.5,inclusive; and preferably about 0.25 to about 0.4, inclusive, A is ananion having a charge of -n; n is an integer in the range of 1 to 6,inclusive, and, m is zero or a positive number, to provide a catalysthaving minimal or no content of free zinc oxide. The hydrotalcite-likecompound (sometimes referred to herein as a "clay") is prepared underconditions of controlled pH and controlled ionic concentrations.

Hydrotalcite-like Compound

Generally speaking, a hydrotalcite-like compound of a formula givenabove may be prepared according to the invention by coprecipitation ofanionic and cationic species from a solution of suitable sources thereofunder conditions of controlled pH and controlled metallic ionconcentrations by procedures such as those known in the art.Coprecipitation creates a gel of the hydrotalcite-material, which may bedried under gentle conditions to provide the hydrotalcite-like compound,which may subsequently be calcined in order to dehydrate the compoundand to decompose the anionic species A, to form a catalyst.

As is apparent from the formula of the clay given above, the clay alwayscontains at least two of Cu²⁺, Ni²⁺, Zn²⁺, and, if at least one of Zn²⁺and Ni²⁺ is also present, Mg²⁺, along with a metal having a valence of3+ selected from Al³⁺, Fe³⁺, Cr³⁺, La³⁺, Ce³⁺, and mixtures thereof.

Generally, the compound will contain copper and/or nickel plus magnesiumand/or zinc. The metals having a valence of 2+ preferably include, incombination, Cu²⁺ and Zn²⁺ ; Cu²⁺ and Ni²⁺ ; Cu²⁺, Ni²⁺, and Zn²⁺ ; Zn²⁺and Ni²⁺ ; or Mg²⁺ and Ni²⁺, and in preferred forms consist essentiallyof or consist of one of these combinations of divalent metal species. Inother forms, additional M²⁺ metals such as Fe²⁺, Cd²⁺, and mixturesthereof may be present in the clay. Any of the additional divalentmetals may omitted, and in one preferred form the clay is substantiallyfree of magnesium.

The M³⁺ metal present in the clay is selected from the group consistingof Al³⁺, Fe³⁺, Cr³⁺, La³⁺, Ce³⁺, and mixtures thereof, and Al³⁺ is thepreferred trivalent metal.

In one form, the trivalent metal consists essentially or consists ofAl³⁺ or another M³⁺ metal. It is preferred that Al³⁺ be present andcomprise at least 30 wt. % and more preferably at least 40 wt. % of thetrivalent metals. In one form, Al³⁺ is present as part of a mixture withat least one of Fe³⁺, Cr³⁺, La³⁺, and Ce³⁺. In one preferred embodiment,the M³⁺ metals comprise Fe³⁺ in mixture with Al³⁺. However, Al³⁺ neednot be present; any of the other trivalent metals may be used alone orin combination with any of the others.

The variable "x" may range from about 0.1 to about 0.5, inclusive, andpreferably is about 0.25 to about 0.4, inclusive.

In the catalyst of the invention copper and, if present, nickel provideshydrocarbon reforming activity. On the other hand, zinc and, if present,Cr³⁺, Fe³⁺, and Fe³⁺ provide good water gas shift activity. Magnesiumalso may function to control the acidity or basicity of the catalyst.One or more of cerium, lanthanum, and cadmium may be added to improvethe physical properties of the catalyst without interfering with theactivities of other metals.

The anionic species A provides structural integrity by forming pillarsor linkages between cationic layers of the clay. A is preferablyselected from the group consisting of CO₃ ²⁻, NO₃ ⁻, SO₄ ²⁻, metalates,polyoxometalates, hydroxides, oxides, acetates, halides, organiccarboxylates, and polycarboxylates, but carbonate (CO₃ ²⁻) is highlypreferred.

In one preferred form, M²⁺ consists essentially of a mixture of Cu²⁺ andZn²⁺, M³⁺ consists essentially of Al³⁺, and A consists essentially ofCO₃ ² -. Highly preferred forms of the inventive hydrotalcite-likecompound are Cu₃ Zn₂ Al₂ (OH)₁₄ CO₃.mH₂ O, Cu₂ NiZnAl₂ (OH)₁₂ CO₃.mH₂ O,Cu₂ Ni₂ Al₂ (OH)₁₂ CO₃.mH₂ O, Mg₃ NiAl₂ (OH)₁₂ CO₃.mH₂ O, Zn₃ NiAl₂(OH)₁₂ CO₃.mH₂ O, Zn₂ Ni₂ Al₂ (OH)₁₂ CO₃.mH₂ O, and Cu₂ NiZnAl₂ (OH)₁₂CO₃.mH₂ O.

To make the hydrotalcite-like clays of the invention, at least onecompound (preferably nitrate, sulfate, or chloride) of the desired M²⁺metal species is combined in solution with at least one compoundcontaining the desired M³⁺ trivalent metal ion species. The solutioncontaining divalent and trivalent metal cations is then mixed with asolution containing the anionic species A^(n-), preferably slowly over atime period of one to two hour(s). The pH of the resulting solution isadjusted with acid or base such that the anionic species desired toprepare the hydrotalcite is stable in the solution. The pH adjustmentpreferably is made in order to keep the pH at 11 or less, mostpreferably at 10 or less, such that the hydrotalcite-like compounds areformed with minimal or no formation of free zinc oxide (ZnO) or otherdivalent metal oxide(s), which have an adverse effect on the performanceof the eventual catalyst in oxygen-containing hydrocarbon reforming.

It may also be desirable to control the concentrations of the divalentand trivalent metals, as too high a metal concentration preventsefficient formation of cationic layers in the clay. Thus, according tothe invention, the total divalent and trivalent metal concentration inthe gel preferably should be maintained at 0.5 moles/liter or less,especially when Zn²⁺ is present.

The lower limits of metals concentrations are dictated only by economicconsiderations. Preferably, the pH of the solution preferably should bemaintained at 5 or greater, and highly preferably 7 or greater.

pH control and metals concentration control are especially important ifZn²⁺ is present, as the tendency to form free metal oxide (ZnO, in thiscase) is relatively great with zinc as compared to other useful metals.The need to control pH and concentration varies directly with the Zn²⁺concentration.

Preferably, respective solutions of the anionic and cationic species aremixed together under the foregoing conditions to produce a gel. Thehydrotalcite-like compound may then be readily obtained by gently dryingthe gel at 100° C. or less, for example.

The Catalyst

The catalyst of the invention is formed by dehydrating thehydrotalcite-like compound and decomposing the anionic species A, as bycalcining. Calcining is carried out at a sufficiently high temperatureand for a period of time sufficient to carry out dehydration, andanionic species decomposition. Generally, calcining may be carried outat a temperature in the range about 250° C. to about 700° C., inclusive,but calcining is preferably carried out at a temperature of at least300° C., highly preferably at about 400° C. to about 550° C., inclusive,and most preferably at a temperature of about 450° C. Activity of thecatalyst will be adversely affected by calcining at too low atemperature, as dehydration may not be complete, and undesiredstructural changes occur at temperatures over 700° C. Reforming activityfor oxygenated hydrocarbon feeds is optimized by calcining in the rangeof 400° C. to 550° C.

Calcining can be carried out under reducing or non-reducing conditions,but it is preferred to calcine the clay under a flow of air or nitrogen.The time necessary for calcining varies inversely with the calciningtemperature, but the calcining time is not critical.

Preparation of the hydrotalcite-like compounds of the invention underthe conditions described above generally results in the formation ofhydrotalcite-like compounds having ZnO and other divalent metal oxidecontents of less than about 1 wt. %, as determined by x-ray diffraction.Substantial contents of ZnO and other divalent metal oxide impuritieshave a negative effect on the performance of the catalyst prepared fromthe hydrotalcite-compound.

Preferably, the catalyst comprises Cu²⁺ and/or Ni²⁺ plus Zn²⁺ and/orMg²⁺, optionally with at least one additional metal having a valence of2+, wherein the divalent copper, nickel, zinc, and magnesium speciestogether comprise at least about 10 wt. % of the divalent metals. Highlypreferably, divalent copper, nickel, zinc, and magnesium togethercomprise about 15 wt. % to about 70 wt. % of the divalent metals, andhighly preferably the copper, nickel, zinc, and magnesium comprise atleast about 30 wt. % of the divalent metals in the catalyst. If desired,copper, nickel, zinc, and magnesium may together form 100 wt. % of thedivalent metals in the catalyst.

It is desirable in some cases that the trivalent metals includetrivalent iron or another trivalent metal in addition to the preferredtrivalent aluminum.

It is difficult to derive a universal idealized formula for the catalystof the invention, but preferred hydrotalcite-like compounds Cu₃ Zn₂ Al₂(OH)₁₄ CO₃.mH₂ O, Cu₂ NiZnAl₂ (OH)₁₂ CO₃.mH₂ O, Cu₂ Ni₂ Al₂ (OH)₁₂CO₃.mH₂ O, Mg₃ NiAl₂ (OH)₁₂ CO₃.mH₂ O, Zn₃ NiAl₂ (OH)₁₂ CO₃.mH₂ O, Zn₂Ni₂ Al₂ (OH)₁₂ CO₃.mH₂ O, and Cu₂ NiZnAl₂ (OH)₁₂ CO₃.mH₂ O, whencalcined, produce preferred catalysts of the formulae Cu₃ Zn₂ Al₂ O₈,Cu₂ NiZnAl₂ O₇, Cu₂ Ni₂ Al₂ O₇, Mg₃ NiAl₂ O₇, Zn₃ NiAl₂ O₇, Zn₂ Ni₂ Al₂O₇, and Cu₂ NiZnAl₂ O₇, respectively.

The skilled artisan can readily prepare catalysts of the desiredidealized formulations by preparing hydrotalcite-like compounds havingatomic ratios of metals that correspond to the idealized formulae of thecatalysts themselves.

Process Conditions

The oxygen-containing hydrocarbon reforming method of the invention isremarkably simple to carry out with high efficiency. In general terms,the hydrocarbon (e.g., methanol) and water are provided to a reactor,preferably in liquid form, to be passed in gaseous form at an elevatedtemperature over a catalyst bed. For example, a catalyst bed may beformed in a tubular reactor maintained at 300° C. or less at any desiredpressure, generally in the range of about one to about 100 atm., andpreferably in the range of about five atm. to 25 atm. It is notnecessary to operate at elevated pressure, but operation in the range ofabout five atm. to about 25 atm. may avoid the need for subsequentcompression of products for downstream processes.

Other types of heterogeneous reactors may be used, as known in the art.

In methanol reforming applications, the reactor is typically operated ata temperature in the range of about 200° C. to about 300° C. (Largeralcohols or other hydrocarbons may require higher reactiontemperatures.) Since the reactor is endothermic in nature, heat may beprovided to the reactor to maintain the reaction temperature. The degreeof conversion is directly related to the reaction temperature, and theuse of lower reaction temperature with recycle may be desirable. It hasbeen found that the catalyst of the invention allows virtually completeconversion of methanol to carbon dioxide and hydrogen products.

The hydrocarbon and water reactants may be provided to the reactor, inliquid form, in any desired ratio; for methanol reforming, a molar H₂O:CH₃ OH range of about 0.5 to about 2 is generally used, although aunimolar ratio is highly preferred. The gaseous hydrocarbon and watermay be carried in a diluent, such as a nitrogen stream, which provides ahomogenous reaction mixture, and assists in controlling the reactiontemperature and thus the reaction rate. The catalyst need not bediluted, supported, or pelletized.

The product streams produced according to the invention will containsubstantial quantities of molecular hydrogen and other useful product(s)(e.g. carbon dioxide or acetic acid), any of which can be recovered forend-use applications, or for further processing. Hydrogen producedaccording to the invention is especially suitable for use as a fuel orfuel additive for relatively clean power generation.

Since the reaction is endothermic, waste heat from any process can beadvantageously recovered for use in this process.

EXAMPLES

The practice in the invention is illustrated by the following detailedexamples, which are not intended to be limiting.

Example 1

Preparation of Cu₃ Zn₂ Al₂ (OH)₁₄ CO₃.4H₂ O

Each of Cu(NO₃)₂.6H₂ O (72.47 g, 0.3 mole), Zn(NO₃)₂.6H₂ O (52.40g, 0.2mole) and Al₂ (NO₃)₃.9H₂ O (75.02 g, 0.2 mole) was dissolved in a 1,000ml aliquot of distilled water to form a cationic solution, and placedinto an addition funnel.

An anionic solution was prepared by dissolving NaOH (56.00 g, 1.4 moles)and Na₂ CO₃ (15.98 g, 0.15 mole 50% molar excess in order to ensurepillaring) in 1,200 ml distilled water. The solution was placed into around bottom three-neck flask.

The cationic solution was added to the anionic solution, with stirring,over a two hour period. Upon completion of addition, the pH was measuredat 10.6, and was then adjusted to 8.25 using nitric acid (HNO₃). Afteradjustment of the pH, the slurry was heated to 85° C. and maintained atthat temperature overnight, with stirring, under a nitrogen purge/sweep.

The precipitated gel-like material was filtered and then washed threetimes with distilled water. Two liters of distilled water were used perwash.

The resulting material was then oven-dried at 70° C. overnight under 22inches of vacuum. The dry weight of the resulting hydrotalcite productwas 57.89 grams.

Preparation of Cu₃ Zn₂ Al₂ O₈ Catalyst

The dried hydrotalcite compound prepared as described above was calcinedby placing the product in a furnace at room temperature, heating at arate of 3° C./minute to a temperature of 550° C., and holding theproduct at 550° C. for four hours. The product was cooled and theresulting Cu₃ Zn₂ Al₂ O₈ catalyst was sieved to 40/60 mesh, to provide acatalyst having an apparent bulk density of 0.65 g/cc.

Methanol Reforming

The Cu₃ Zn₂ Al₂ O₈ catalyst prepared as described above was tested formethanol reforming activity in a 9 mm×11 mm×30 inch quartz tubularreactor. The catalyst bed length was 1.5 inches (volume 2.0 cc) and thecatalyst was not diluted. The catalyst was flanked by a 1/2 inchα-alumina (30/50 mesh) preheat zone and a 1/4 inch α-alumina (30/50mesh) post heat zone.

A thermocouple located at or near the midpoint of the bed was utilizedas a control point for determining when the reactor temperature hadstabilized.

The reactor was purged with 33 std. cc/min of N₂ until the interiortemperature reached 240° C. At 240° C., the feed solution was added at arate of 4.964 cc/hr (0.0827 cc/min). The molar proportions of methanol,water, and nitrogen (N₂) charged to the reactor were about 1:1:1. Thegas hourly space velocity (GHSV) of the feed was 2000, while the GHSV ofthe feed and nitrogen carrier was 3000.

The product stream flowing from the reactor was analyzed, and theresults are shown in the table, below.

    __________________________________________________________________________    Cu.sub.3 Zn.sub.2 Al.sub.2 O.sub.8 Methanol Reforming Catalyst                Day     1    1    2    3    3    3    3    4    5                             Time:   13:47                                                                              18:13                                                                              6:12 7:04 9:27 12:14                                                                              19:26                                                                              6:09 6:10                          __________________________________________________________________________    Temp. (° C.)                                                           Exterior                                                                              261  261  261  261  286  286  286  286  286                           Interior                                                                              238  240  240  238  257  258  259  259  258                           Product                                                                       (mole %)                                                                      H.sub.2 56.757                                                                             56.424                                                                             56.184                                                                             55.843                                                                             59.637                                                                             58.86                                                                              59.267                                                                             59.363                                                                             58.856                        N.sub.2 22.308                                                                             22.745                                                                             23.335                                                                             23.913                                                                             19.606                                                                             20.205                                                                             20.155                                                                             20.101                                                                             20.2                          CO      0.808                                                                              1.11 0.944                                                                              0.5  0.746                                                                              1.309                                                                              0.831                                                                              0.705                                                                              0.786                         CH.sub.4                                                                              0.0543                                                                             0.0667                                                                             0.0441                                                                             0.0204                                                                             0    0    0    0    0.0227                        CO.sub.2                                                                              18.165                                                                             17.947                                                                             17.72                                                                              17.587                                                                             18.473                                                                             18.237                                                                             18.415                                                                             18.43                                                                              18.349                        C2s     0    0    0    0    0    0    0    0    0                             H.sub.2 O                                                                             0.537                                                                              0.557                                                                              0.438                                                                              0.432                                                                              0.457                                                                              0.422                                                                              0.523                                                                              0.56 0.638                         C3s     0    0    0    0    0    0    0    0    0                             DME     0    0    0    0    0    0    0    0    0                             CH.sub.3 OH                                                                           1.372                                                                              1.149                                                                              1.335                                                                              1.705                                                                              1.081                                                                              0.966                                                                              0.808                                                                              0.841                                                                              1.149                         Mole Ratio                                                                    H.sub.2 /CO.sub.2                                                                     3.12 3.14 3.17 3.18 3.23 3.23 3.22 3.22 3.21                          H.sub.2 /(CO + CO.sub.2)                                                              2.99 2.96 3.01 3.09 3.10 3.01 3.08 3.10 3.08                          H.sub.2 /(total carbon)                                                               2.98 2.95 3.00 3.08 3.10 3.01 3.08 3.10 3.07                          Conversion (%)                                                                MeOH    97.24                                                                              97.69                                                                              97.32                                                                              96.58                                                                              97.83                                                                              98.06                                                                              98.38                                                                              98.31                                                                              97.69                         Selectivity (%)                                                               H.sub.2 99.81                                                                              99.76                                                                              99.93                                                                              100.00                                                                             100.00                                                                             100.00                                                                             100.00                                                                             100.00                                                                             99.92                         CO      4.25 5.80 5.05 2.76 3.88 6.70 4.32 3.68 4.10                          CH.sub.4                                                                              0.29 0.35 0.24 0.11 0.00 0.00 0.00 0.00 0.12                          CO.sub.2                                                                              95.47                                                                              93.85                                                                              94.72                                                                              97.13                                                                              96.12                                                                              93.30                                                                              95.68                                                                              96.32                                                                              95.78                         __________________________________________________________________________

Example 2

Preparation of Cu₂ Ni₂ Al₂ (OH)₁₂ CO₃.xH₂ O

Each of Cu(NO₃)₂.6H₂ O (17.44 g, 0.075 mole), Ni(NO₃)₂.6H₂ O (21.81 g,0.075 mole), and Al(NO₃)₃.9H₂ O (28.14 g, 0.075 mole) was dissolved in a350 mL aliquot of distilled water to form a cationic solution, andplaced in an addition funnel.

An anionic solution was prepared by dissolving NaOH(18.00 g, 0.45 mole)and Na₂ CO₃ (7.93 g, 0.075 mole) (one equivalent excess in order toensure pillaring) in 400 mL of distilled water. The resulting solutionwas placed in a round bottom three-neck flask.

The cationic solution as added to the anionic solution, while stirring,over a two hour period. Upon completion of addition, the pH was measuredat about 10, and was then adjusted to 8.66 using nitric acid (HNO₃).After adjustment of the pH, the slurry was heated to 85° C. andmaintained at that temperature overnight, with stirring, under anitrogen purge/sweep.

The precipitated gel-like material was filtered, and washed withdistilled water three times. About one liter of distilled water was usedper wash. The resulting gel was then oven-dried at 70° C. overnightunder 22 inches (Hg) of vacuum. The dry weight of the resultinghydrotalcite product was 21.79 g.

Preparation of Cu₂ Ni₂ Al₂ O₇

The dried hydrotalcite compound prepared as described above was calcinedby placing the product in a furnace at room temperature, heating at arate of 3° C./min. to a temperature of 450° C., and holding the productat that temperature for three hours to produce Cu₂ Ni₂ Al₂ O₇ catalyst.

Example 3

Preparation of Mg₃ NiAl₂ (OH)₁₂ CO₃.xH₂ O

Each of Mg(NO₃)₂.6H₂ O (28.85 g, 0.1125 mole), Ni(NO₃)₂.6H₂ O (10.91 g,0.0375 mole), and Al(NO₃)₃.9H₂ O (28.14 g, 0.075 mole) was dissolved ina 350 mL aliquot of distilled water to form a cationic solution, andplaced in an addition funnel.

An anionic solution was prepared by dissolving NaOH(18.00 g, 0.45 mole)and Na₂ CO₃ (7.93 g, 0.075 mole) (one equivalent excess in order toensure pillaring) in 400 mL of distilled water. The resulting solutionwas placed in a round bottom three-neck flask.

The cationic solution was added to the anionic solution, while stirring,over a two hour period. Upon completion of addition, the pH was adjustedto 9.0 using nitric acid (HNO₃). After adjustment of the pH, the slurrywas heated to 85° C. and maintained at that temperature overnight, withstirring, under a nitrogen purge/sweep.

The precipitated gel-like material was filtered, and washed withdistilled water three times. About one liter of distilled water was usedper wash. The resulting gel was then oven-dried at 70° C. overnightunder 22 inches (Hg) of vacuum. The dry weight of the resultinghydrotalcite products was 18.25 g.

Preparation of Mg₃ NiAl₂ O₇

The dried hydrotalcite compound prepared as described above was calcinedby placing the product in a furnace at room temperature, heating at arate of 30° C./min. to a temperature of 450° C., and holding the productat that temperature for three hours to produce Mg₃ NiAl₂ O₇ catalyst.

Example 4

Preparation of Zn₃ NiAl₂ (OH)₁₂ CO₃.H₂ O

Each of Zn(NO₃)₂.6H₂ O (29.41 g, 0.1125 mole), Ni(NO₃)₂.6H₂ O (10.91 g,0.0375 mole), and Al(NO₃)₃.9H₂ O (28.14 g, 0.075 mole) was dissolved ina 350 mL aliquot of distilled water to form a cationic solution, andplaced in an addition funnel.

An anionic solution was prepared by dissolving NaOH (18.00 g, 0.45 mole)and Na₂ CO₃ (7.93 g, 0.075 mole) (one equivalent excess in order toensure pillaring) in 400 mL of distilled water. The resulting solutionwas placed in a round bottom three-neck flask.

The cationic solution was added to the anionic solution, while stirring,over a two hour period. Upon completion of addition, the pH was adjustedto 8.3 using nitric acid (HNO₃). After adjustment of the pH, the slurrywas heated to 88° C. and maintained at that temperature overnight, withstirring, under a nitrogen purge/sweep.

The precipitated gel-like material was filtered, and washed withdistilled water three times. About one liter of distilled water was usedper wash. The resulting gel was then oven-dried at 70° C. overnightunder 22 inches (Hg) of vacuum. The dry weight of the resultinghydrotalcite product was 24.25 g.

Preparation of Zn₃ NiAl₂ O₇

The dried hydrotalcite compound prepared as described above was calcinedby placing the product in a furnace at room temperature, heating at arate of 3° C./min. to a temperature of 450° C., and holding the productat that temperature for three hours to produce Zn₃ NiAl₂ O₇ catalyst.

Example 5

Preparation of Zn₂ Ni₂ Al₂ (OH)₁₂ CO₃.xH₂ O

Each of Zn(NO₃)₂.6H₂ O (22.31 g, 0.075 mole), Ni(NO₃)₂.6H₂ O (21.81 g,0.075 mole), and Al(NO₃)₃.9H₂ O (28.14 g, 0.075 mole) is dissolved in a350 mL aliquot of distilled water to form a cationic solution, andplaced in an addition funnel.

An anionic solution is prepared by dissolving NaOH (18.00 g, 0.45 mole)and Na₂ CO₃ (7.93 g, 0.075 mole) (one equivalent excess in order toensure pillaring) in 400 mL of distilled water. The resulting solutionis placed in a round bottom three-neck flask.

The cationic solution is added to the anionic solution, while stirring,over a two hour period. Upon completion of addition, the pH is measuredat about 10, and is then adjusted to 8.5 using the nitric acid (HNO₃).After adjustment of the pH, the slurry is heated to 85° C. andmaintained at that temperature overnight, with stirring, under anitrogen purge/sweep.

The precipitated gel-like material is filtered, and washed withdistilled water three times. About one liter of distilled water is usedper wash. The resulting gel is then oven-dried at 70° C. overnight under22 inches (Hg) of vacuum. The dry weight of the resulting hydrotalciteproduct is about 22 g.

Preparation of Zn₂ Ni₂ Al₂ O₇

The dried hydrotalcite compound prepared as described above is calcinedby placing the product in a furnace at room temperature, heating at arate of 3° C./min. to a temperature of 450° C., and holding the productat that temperature for three hours to produce Zn₂ Ni₂ Al₂ O₇ catalyst.

Example 6

Preparation of Cu₂ NiZnAl₂ (OH)₁₂ CO₃.xH₂ O

Each of Cu(NO₃)₂.6H₂ O (17.44 g, 0.075 mole), Ni(NO₃)₂.6H₂ O (10.9 g,0.0375 mole), Zn(NO₃)₂.6H₂ O (11.15 g, 0.0375 mole), and Al(NO₃)₃.9H₂ O(28.14 g, 0.075 mole) is dissolved in a 350 mL aliquot of distilledwater to form a cationic solution, and placed in an addition funnel.

An anionic solution is prepared by dissolving NaOH (18.00 g, 0.45 mole)and Na₂ CO₃ (7.93 g, 0.075 mole) (one equivalent excess in order toensure pillaring) in 400 mL of distilled water. The resulting solutionis placed in a round bottom three-neck flask.

The cationic solution is added to the anionic solution, while stirring,over a two hour period. Upon completion of addition, the pH is measuredat about 10, and is then adjusted to about 8.5 using nitric acid (HNO₃).After adjustment of the pH, the slurry is heated to 85° C. andmaintained at that temperature overnight, with stirring, under anitrogen purge/sweep.

The precipitated gel-like material is filtered, and washed withdistilled water three times. About one liter of distilled water is usedper wash. The resulting gel is the oven-dried at 70° C. overnight under22 inches (Hg) of vacuum. The dry weight of the resulting hydrotalciteproduct is about 22 g.

Preparation of Cu₂ NiZnAl₂ O₇

The dried hydrotalcite compound prepared as described above is calcinedby placing the product in a furnace at room temperature, heating at arate of 3° C./min. to a temperature of 450° C., and holding the productat that temperature for three hours to produce Cu₂ NiZnAl₂ O₇ catalyst.

The foregoing detailed description is given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications within the scope of the invention may becomeapparent to those skilled in the art.

I claim:
 1. A method of reforming an oxygen-containing hydrocarbonselected from the group consisting of ethers, alcohols, C₂ -C₄aldehydes, and C₂ -C₄ ketones, said method comprising the step ofpassing a feed stream comprising said hydrocarbon and water over acatalyst under reforming conditions including a reforming temperature ofabout 300° C. or less wherein said hydrocarbon is reformed, saidcatalyst being formed by(a) providing a hydrotalcite-like compound ofthe formula [M²⁺.sub.(1-x) M³⁺ ^(x) (OH)₂ ]^(x+) (A^(n-) _(x/n)).mH₂ O,wherein M²⁺ comprises at least two species of metal ions having avalence of 2+ selected from the group consisting of Cu²⁺, Zn²⁺, Ni²⁺,and Mg²⁺, provided that if M²⁺ comprises Mg²⁺ at least one of Zn²⁺ andNi²⁺ is also present, wherein the atomic ratio of the total of Zn²⁺ andMg²⁺ to the total of Cu²⁺ and Ni²⁺ is up to about 9, inclusive, andwherein the total of Zn²⁺ and Mg²⁺ comprises at least about 5 wt. % ofsaid M²⁺ metals; M³⁺ comprises at least one metal ion having a valenceof 3+ selected from the group consisting of Al³⁺, Fe³⁺, Cr³⁺, La³⁺,Ce³⁺, and mixtures thereof; x is a number in the range of about 0.1 toabout 0.5, inclusive; A is an anion having a charge of -n and isdecomposable at a temperature of 550° C. or less; n is an integer in therange of 1 to 6, inclusive; and, m is zero or a positive number, and (b)heating said compound at a temperature of 550° C. or less for a timesufficient to decompose A and to dehydrate said compound to form saidcatalyst.
 2. The method of claim 1 comprising the step of heating saidhydrotalcite-like compound at a temperature of about 400° C. to about550° C., inclusive.
 3. The method of claim 1 wherein M²⁺ comprises amixture of Cu²⁺ and Zn²⁺ with at least one additional metal species ofions having a valence of 2+.
 4. The method of claim 3 wherein saidadditional species of metal ions having a valence of 2+ is selected fromthe group consisting of Mg²⁺, Fe²⁺, Ni²⁺, Cd²⁺, and mixtures thereof. 5.The method of claim 1 wherein M²⁺ consists essentially of Cu²⁺ and Zn²⁺.6. The method of claim 1 wherein said compound is substantially free ofmagnesium.
 7. The method of claim 1 wherein M²⁺ comprises Zn²⁺ and saidcompound is formed by coprecipitating said compound from an aqueoussolution containing said ions M²⁺, M³⁺, and A^(n-) at a pH of 11 or lessand a total concentration of M²⁺ and M³⁺ of 0.5 moles per liter or lessto form a gel, and drying said gel to form said compound.
 8. The methodof claim 1 wherein Al³⁺ comprises about 30 wt. % to about 100 wt. % ofsaid M³⁺ metals.
 9. The method of claim 8 wherein Al³⁺ comprises atleast about 40 wt. % of said M³⁺ metals.
 10. The method of claim 1wherein M³⁺ consists essentially of Al³⁺.
 11. The method of claim 1wherein M³⁺ comprises a mixture of Al³⁺ and at least one member selectedfrom the group consisting of Fe³⁺, Cr³⁺, La³⁺, and Ce³⁺.
 12. The methodof claim 11 wherein M³⁺ comprises Fe³⁺ in addition to said Al³⁺.
 13. Themethod of claim 1 wherein the atomic ratio of the total of Zn²⁺ and Mg²⁺to the total of Cu²⁺ and Ni²⁺ is in the range of about 0.3 to about 5,inclusive.
 14. The method of claim 1 wherein x is a number in the rangeof about 0.25 to about 0.4, inclusive.
 15. The method of claim 1 whereinA is selected from the group consisting of CO₃ ²⁻, NO₃ ⁻, SO₄ ²⁻,metalates, polyoxometalates, hydroxides, oxides, acetates, halides,organic carboxylates, and polycarboxylates.
 16. The method of claim 15wherein A is CO₃ ²⁻.
 17. The method of claim 1 wherein said M²⁺ consistsessentially of Cu²⁺ and Zn²⁺, said M³⁺ consists essentially of Al³⁺, andA consists essentially of CO₃ ²⁻.
 18. The compound of claim 1 whereinsaid compound is selected from the group consisting of Cu₃ Zn₂ Al₂(OH)₁₄ CO₃.mH₂ O, Cu₂ NiZnAl₂( OH)₁₂ CO₃.mH₂ O, Cu₂ Ni₂ Al₂ (OH)₁₂CO₃.mH₂ O, Mg₃ NiAl₂ (OH)₁₂ CO₃.mH₂ O, Zn₃ NiAl₂ (OH)₁₂ CO₃.mH₂ O, Zn₂Ni₂ Al₂ (OH)₁₂ CO₃.mH₂ O, and Cu₂ NiZnAl₂ (OH)₁₂ CO₃.mH₂ O.
 19. Themethod of claim 1 wherein said catalyst is selected from the groupconsisting of Cu₃ Zn₂ Al₂ O₈, Cu₂ NiZnAl₂ O₇, Cu₂ Ni₂ Al₂ O₇, Mg₃ NiAl₂O₇, Zn₃ NiAl₂ O₇, Zn₂ Ni₂ Al₂ O₇, and Cu₂ NiZnAl₂ O₇.
 20. The method ofclaim 1 wherein said hydrocarbon is selected from the group consistingof dimethyl ether, diethyl ether, methyl ethyl ether, methanol, ethanol,propanols, and butanols.
 21. The method of claim 1 wherein saidhydrocarbon is methanol.
 22. The method of claim 1 wherein saidhydrocarbon is ethanol.